Duchenne muscular dystrophy (DMD) is a lethal genetic disease that affects 1 in 3,500 boys. Accumulating evidence from multiple laboratories corroborate on the involvement of calcium misregulation and oxidative stress as key contributors to the disease, suggesting that upregulation of calcium-sequestering (CaSeq) or anti-oxidant (Antiox) pathways may serve as targets in the treament of DMD. The present application aims to identify the CaSeq/Antiox pathways most significant to the dystrophic phenotype, and assess the therapeutic potential that can be realized by a gene therapy designed to target these pathways. The project is framed by three specific aims and will utilize two murine models of DMD: the mdx and mdx:utrn-/- strains. In Aim 1, muscle cells and isolated muscle preparations will be used characterize the impact of individual CaSeq/Antiox pathways on the dystrophic phenotype. CaSeq/Antiox pathways with the most substantial impact will then be used as targets for viral-mediated gene therapies. To evaluate the efficacy of these gene therapies, dystrophic mice will be injected intravenously with recombinant adeno-associated viruses that contain CaSeq/Antiox transgenes. We will determine whether these transgenes can extend the lifespan of dystrophic mice and correct the pathophyosiology associated with dystrophin-deficiency. Although the scope of the application remains focused on DMD, we expect the therapeutic aspect of our findings to have a direct relevance in the treatment of other diseases where calcium misregulation or oxidative stress play a key role, such as Alzheimer's Disease, aging, diabetes and cardiovascular disease. In the final Aim of the application, we generate mutant mdx mice with modified CaSeq/Antiox pathways by crossing mdx mice with existing strains of mice that possess modified CaSeq/Antiox pathways. These mutant mdx mice will be valuable additions to current dystrophic mouse models, as they allow investigators to isolate the contribution of specific CaSeq/Antiox pathways to the dystrophic phenotype.